1. Field of the Invention
The present invention relates to an integrated circuit (IC) chip having testing circuits and a method of testing the same and, more particularly, to an IC chip with testing circuits which can be tested even alter packaged on a circuit board, and a method of testing the same.
2. Description of the Related Art
IC chips including large scale integrated circuit (LSI) chips are usually tested by an IC checker or similar testing device before shipment to see if their functions are normal. Specifically, the test result is compared with, for example, a test pattern provided at the designing stage. With a logic IC chip, for example, it is a common practice to input desired data in the IC chip via the input terminal of the IC chip and determine whether or not expected data appears on the output terminal of the IC chip. It is, therefore, possible to fully test IC chips one by one before packaging on a circuit board. However, the problem with conventional IC chips is that when a plurality of chips are packaged on a single circuit board, they cannot be checked or tested one by one due to their mutual influence as well as the influence of surrounding elements, particularly the connections thereof. Assume that after all the IC chips and surrounding elements have been mounted on a circuit board, an error occurs during actual drive. Then, a defective IC chip or a defective wiring cannot be located on the circuit board. The only measure left is to remove all the IC chips from the circuit board and then test them one by one while testing the wirings again which increases the cost due to additional time and labor.